> Allow me to quote from Dana and Mantey, A Manual Grammar
> Of The Greek New Testament, from the section "The Special
> Uses of the Article," p. 147:
>
> (1) WITH NOUNS CONNECTED BY KAI. The
> following rule by Granville Sharp of a century back
> still proves to be true: "When the copulative KAI
> connects two nouns of the same case, if the article hO
> or any of its cases precedes the first of the said nouns
> or participles, and is not repeated before the second
> noun or participle, the latter always relates to the same
> person that is expressed or described by the first noun
> or participle; i.e., it denotes a farther description of the
> first-named person."

As Dan Wallace points out in his forthcoming grammar, Dana and Mantey omit to
mention the specific limitations placed by Sharp on the type of construction he
had in mind. In order for the two substantives to be considered as referring to
the same person in an article-substantive-kai-substantive construction, there
are three specific criterion which must be met:

1. Neither should be impersonal.
2. Neither should be plural.
3. Neither should be a proper name.

Note that in regard to your question about participles, we are talking about
substantives here. (See Wallace's grammar for an excellent discussion of this
material - this was the topic of his doctoral dissertation.)

A look at the text in question would seem to indicate that it does in fact fit
the profile of a Granville Sharp construction, and that hO PISTEUSAS and (hO)
BAPTISQEIS are, in fact, the one and the same person. However, I must admit
that I'm not sure how this impinges on canonicity?!